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Jedmag 12-29-2011 09:57 AM

Shower water pressure low/stopped after water heater repair
Hello everyone

I'm a huge noob on this type of work, but have a father that can help me with anything if we find an answer. I bought my house about a year ago, and after the house inspection I was told I needed to have the corroded nipples on the water heater replaced and so I had this done. Since then the water pressure in my guest shower was terrible, and is now non-existent/small trickle.

It does the same on the bathtub spout as well as the shower head, so it is not the aerator or screen that is clogged. Also, the sink and toilet in this room have excellent water pressure as well as the rest of the house it is only this shower having issues. Also, at times I can hear knocking in the wall after trying to use this shower so in guessing this is air in the line maybe? It gets VERY loud at times. I dont use this shower anymore of course, so the knocking has not happened but just a few times.

I'm open to any suggestions, so please anyone with any info it will graciously be accepted. I'm not going to tear anything up and make it worse,so if it seems over our heads I will hire someone to look at it but wanted try here first.

Thanks in advance!!

TheEplumber 12-29-2011 10:13 AM

199 Attachment(s)
Turn off the water and relieve the pressure. Then pull the shower cartridge and clean or replace it.

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Lightfoot 12-29-2011 10:14 AM

It's not air. Water pressure would push that out in a second. You likely have some trash in the lines which is getting caught up somewhere behind the stems/cartridge which is stopping flow when you turn it on. You didn't say what type of setup you have, but if you post some pix i'm sure someone here can walk you through cleaning it out.

Jedmag 12-29-2011 10:44 AM

Thank you all so much for your quick replies, I will take pictures when I return home of my shower setup. I really appreciate it.


Billy_Bob 12-29-2011 11:41 AM

Remove the cartridge(s), then briefly turn the water on/off. Clean cartridges.

Best to have someone at the bath with a bucket when water is turned on/off. Then if water sprays across, it can be diverted downward with the bucket.

You should see some particles/gunk on the tub floor after doing this.

Next if you have a center valve for shower/bath, remove that cartridge and turn on hot, then cold to flush that out as well.

Jedmag 12-29-2011 12:10 PM

here's some pics i took w/ my iphone (being a photographer, it kills me to post these...yuck!...and as you can kindof see, there is a bunch of trash that has already fallen out of the fawcett into the tub. It's got to be nasty in there somewhere)



by shower cartridges, I'm guessing you mean taking off the hot/cold knobs and removing the pipe going from the handle to the water line? (dumb question i know).

thanks again everyone!

AllanJ 12-29-2011 01:51 PM

Yes, for your setup "removing the cartridge" would correspond to taking off the knobs and then taking out the shafts (stems) as if to change the washers. With one stem back in almost hand tight and the other still out and the shower curtain closed ,briefly turn the water on to see if debris shoots out. Repeat for the other stem.

Before putting the collar and stem assembly back in, hold the collar and twist the stem all the way to the out or on position (usually counterclockwise). Or make sure the stem twists back and forth in the collar reasonably easily all the while you are tightening the collar (fraction of a turn at a time) back into place.

Billy_Bob 12-29-2011 01:57 PM

This is the basic idea...
(Valves are different.)

how 12-29-2011 05:56 PM

When ever you replace HWT pipe nipples or do any soldering work on a plumbing system, you need to refill the system leaving one prepared exit open to flush out the debris caused by the plumbing work. A tap with the resister/filter removed will do.

Jedmag 01-04-2012 04:42 PM


I finally had time to try this and no luck.

Here's what I have done:
I turned the water off and remove the hot and cold cartridges/hardware and then turned the water back on and water was flowing very well out of the hot/cold pipes. Put the cartridges back in and both out of the faucet and the shower head the pressure is terrible.

Leads me to believe the clog is between the "T" after the hot/cold "t" to the faucett. That's where I'm stuck. What to do now?

I humbly request your opinions. Thank you all so much

TarheelTerp 01-04-2012 04:56 PM


Originally Posted by Jedmag (Post 812494)
Put the cartridges back in and both out of the faucet and the shower head the pressure is terrible.

So to repeat... the tub spout has plenty of flow?
Then you still have junk in the faucet or the riser pipe hanging up.


Billy_Bob 01-04-2012 05:10 PM

Well this is going to involve some creative thinking!

If there is an access hatch behind the bath faucet, then you could remove the shower head and arm and the bath spout and disassemble the whole faucet, then clean the T...

However, I have an easier idea which I have never tried. Some of these have a plastic strainer like thing in the T would certainly collect particles and stop water from flowing.

Perhaps you could "back flush" that?

So here is my idea... If you can turn off just the water to the house. And can leave the outside water on. And have a garden hose. And it is not freezing cold outside and the outside faucet frozen...

Then get a garden hose "male" to 1/2" pipe "male" adapter (which I assume your shower head is). Then remove the shower head and install that adapter on the shower arm where the shower head was.

Run the garden hose inside and connect it to the shower head adapter on the shower head arm.

Turn off the inside water.

Remove the hot and cold cartridges again.

Turn on the outside water hose. That will force water backwards through the shower head and out through the T, and then out where the cartridges were. Hopefully unclogging it.

Then some of those particles might hang around where the cartridges go, so turn on the inside water again to flush that. Then off again. Then outside hose off.

Then reinstall the cartridges. Turn water back on and see if it works.

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